Barely two years after bringing his bucket and mop to the mess that is Nissan’s Infiniti luxury car division, boss and former Audi of America chief Johan de Nysschen has resigned and will be taking his cleaning supplies back to America as president of Cadillac. In his wake at Infiniti is a job that is, at best, only partially finished, while tumultuous Cadillac gets its third leader in two years.

Becoming the second consecutive Nissan exec to join Cadillac—the last, former Nissan Australia CEO Bill Pfeffer, quit as Cadillac’s sales boss in June just 10 months after taking the job—de Nysschen has his work cut out. The brand’s executive suite has been roiling while sales of Cadillacs in the U.S. are flat at best. The compact ATS and full-size XTS sedans are particular millstones around the division’s neck. According to the trade magazine Automotive News, the ATS had a 164-day supply in inventory as of July 1, while the XTS had a 172-day supply and the new CTS had a whopping a 195-day supply, against the industry average for non-trucks of just 57 days. (Infiniti’s average supply for its cars stands at 107 days).

Cadillac dealers have been begging GM for leadership stability, preferably with a company outsider headhunted from one of the market’s leading luxury divisions. That’s partly because outgoing global brand chief Bill Ferguson, formerly GM’s top lobbyist in Washington, D.C., has been spending so much time sitting in Congressional hearings helping new GM CEO Mary Barra through the ignition-switch recall. Cadillac has been left to swing in the wind, and GM recently acknowledged a fait accompli and sent Ferguson back to his old job in D.C., thus opening up the spot for de Nysschen.

A general globalizing and sprucing up of Cadillac can thus be expected, with more initiatives aimed at putting the brand on a world stage. So, expect products positioned to sell internationally and particularly in China. The problem is that Cadillac has already tried a number of those ideas over the years, including replacing its historic names with three-letter alphanumerics, creating a performance V sub-brand, re-skinning Saabs for sale on the Continent, and racing at Le Mans. All have delivered no more than mixed success, no doubt because they were executed haphazardly. Expect de Nysschen’s first contribution to be an organized strategy.

However, with its newest cars, the ATS and CTS, built on platforms that are already competitive for curb weight and handling, what Cadillac needs most desperately is a stable of world-class powertrains. Currently, Cadillac uses corporate hand-me-downs, including a 3.6-liter V-6 that is just a bit too large, a 2.0-liter turbo inline-four that is a bit too rough, and a 2.5-liter base four cylinder from the Chevy Malibu that is definitely way too Malibu for a Cadillac. Only the CTS Vsport’s twin-turbo V-6 feels appropriate for the class.

However, replacing those engines entails billion-dollar investments that de Nysschen may not have the pull or persuasion to make happen at lumbering, cost-conscious GM. And working over Cadillac’s traditional dealer body to bring it up to the sales and service standards of Lexus or Mercedes-Benz will involve getting lots of players to move in concert, a task that has befuddled many of de Nysschen’s predecessors.

Whatever the man does, he’s going to need more than two years to pull it off. Let’s hope he stays a bit longer in this job.